This invention relates to a conveying system for use with a continuous mining machine for continuously moving mined material such as coal from the auger or cutting head to the rear or discharge end of the machine for transporting out of the mine. More particularly, this invention relates to a conveying system suitable for use with a continuous narrow seam coal mining machine having a dozer type gathering head. Since mining machines are operated in harsh, wet and corrosive environments, and are required to remove tons of material each day, it is advantagous to keep the number of moving parts in any mining machine to a minimum to reduce the necessary maintenance and repair. However, because of space limitations and lower cost requirements which are further imposed on low seam machines, the need for reduced maintenance is of even greater importance.
There are several types of conveying systems used with modern mining machines. These systems include multistage continuous conveyors having mat chains as the front stage and flight bars as the back stage; flight bar conveyors driven by a single centrally located chain, and flight bar conveyors which may curve in the middle of their travel to bend around corners. Various types of these different conveying systems are described for example in U.S. Pat. Nos. 3,044,753 issued to A. G. Wilcox, Jr., July 17, 1962; 3,116,914 issued to W. G. Young et al, Jan. 7, 1964; 3,161,439 issued to J. S. Newton et al, Dec. 15, 1964; 3,774,969 issued to M. K. Lebegue, Nov. 27, 1973; 3,860,291, issued to Rauch et al, Jan. 14, 1975; and 3,892,443 issued to E. M. Arentezen, July 1, 1975.
The Wilcox U.S. Pat. No. 3,044,753, discloses a continuous mining machine having a full width cutting head or auger which may be pivoted so that it can mine seams which may be classified as medium to high. The machine includes a containing structure having upwardly U shaped sides within which ride flight bars which are attached at their center points to an endless chain. The material cut from the seam by the auger head is conveyed by a gathering head to the flight bar conveying system. The gathering head includes a helical or gathering scroll having an axis parallel with the axis of the cutting auger. The helical scroll cooperates with a conveyor pan to move coal or mined material which has been dislodged along the length of the cutting auger and fallen on the floor of the mine to the center of the machine such that it can be picked up by the flight bar conveyor. The helical scroll is driven by a driving means located close therewith, which in turn provides a sprocket driven to the single centrally located chain of the flight bar conveying system. It should be noted, that the scoop and helical gathering systems is of significant importance with this type of mining machine since the auger cutting head may pivot a significant distance away from the gathering system and thus the cutting auger cannot serve to move the mined material from the edges of the machine to the center of the machine.
The U.S. Pat. No. 3,116,914 issued to Young et al, includes a conveying system essentially the same as that disclosed in the Wilcox patent. However, in addition, the conveying flight bar system of this Young et al patent has flexible sides so that the conveyor may be made to bend in the middle area and thereby convey mined material or coal around a curve. In addition, the Young et al patent describes a different type cutting head. According to the Young patent, removal or dislodging of material to be mined is accomplished by a "ripper head" which comprises a series of toothed continuous chains which are urged forward to engage the material being mined. As was the case with respect to the Wilcox patent, it is of significant importance to note that the gathering system of this invention also uses a helical or scroll gathering head which works in cooperation with a scoop that rides or scrapes along the floor of the mine. Thus, as the mining machine moves forward, coal is dislodged and falls onto the floor of the mine, is scraped into the scoop and is then conveyed towards the center of the mining machine by the scroll gathering head where it is picked up by the flight bars and conveyed to the rear of the machine for subsequent transporting out of the mine.
The mining machine disclosed by U.S. Pat. No. 3,161,439 issued to Newton et al, also discloses a conveyor system similar to that disclosed in both the Wilcox and the Young et al patents. However, this patent discloses still a third type of cutting head. The cutting head of the Newton et al patent is of the side cutting auger type. However, as was the case with the previously discussed patents, of significant importance and consideration is the use of the helical or scroll gathering head which operates in cooperation with a scoop which in turns rubs or scrapes against the floor of the mine such that dislodged material is picked up by the scoop and moved towards the center of the mining machine by the helical head from which center it is then picked up by the gathering head and moved to the rear of the machine.
U.S. Pat. No. 3,774,969 issued to Lebegue shows yet another type mining machine which uses a conveyor system similar to that discussed with respect to the Wilcox, Young et al and Newton et al machines. This mining machine uses yet another type of cutting or auger head. However, as was the case with the previously discussed patents a helical or spiral gathering system is used in cooperation with a scoop which rubs or scrapes along the bottom of the mine and picks up material which is conveyed to the center of the machine where it is further picked up by the flight bar conveying system and routed to the rear of the machine where it is discharged.
Thus, it is seen from the mining machines discussed heretofore, a flight bar conveying system is disclosed which works in conjunction with a helical scroll and scoop gathering system. It will also be noted that the flight bar conveying system of each of the discussed patents uses a single chain to which the flight bars are attached at the center points. In addition, the chain and flight bars accomplish a 180.degree. turn around by means of a sprocket having a diameter the same as the helical gathering head. It will also be appreciated that the cost of the helical scroll and scoop gathering head is not insignificant.
U.S. Pat. Nos. 3,860,291 and 3,892,443 issued to Rauch et al and Arentezen respectively and each assigned to Dresser Industries disclose two aspects of a gathering system different from that heretofore discussed. The mining machine according to these two patents uses a auger type cutting head similar to that discussed wih respect to the Wilcox patent. However, the Dresser patents use an entirely different type of gathering system. The gathering system of the Dresser patents is referred to as a dozer type gathering system. The dozer type gathering system has been found particularly suitable for use with machines primarily used in mining very narrow seams of coal. According to this gathering system, the cutting auger itself works in cooperation with a backup panel and a dozer head or blade to gather the coal. In addition, the conveying system itself always remains in close proximity to the cutting head. Since the dozer blade or backup panel is always located only a short distance away from the auger cutting head itself, it will be appreciated that according to this technique and because of the close proximity of the dozer blades and backup panels, as the mined material is cut loose from the mine face it cannot fall a significant distance from the cutting auger and therefore the auger head itself working in conjunction with the backup panel or dozer head serves to convey the mined material toward the center of the machine. Once at the center of the machine, a "window" or "throat" in the dozer blade and backup panel, allows the coal to accumulate on a front conveyor. The conveyor system of the Dresser machine uses a front continuous conveyor and a rear continuous conveyor such that coal must be transferred from the front conveyor system which works in close proximity to the cutting auger head to the rear continuous conveying system. This front portion is a chain mat type continuous conveyor. The chain mat thus conveys coal from the auger cutting head to the rear of the first conveyor where the coal is then transferred to the rear conveyor which is a flight-bar continuous conveyor. A pivot proximate the location where the front and rear continuous conveyor systems meet, allows the front conveyor system to pivot such that it can follow and thus stay close to the cutting auger heads. Although mining machines of this type are widely used as a narrow seam mining machine, the chain mat conveying system presents continuous problems in maintenance. Experience has shown, that the chain mat front conveyor requires continuous servicing and maintenance. The chain mats also represent the one item requiring the most short term replacement. In addition because the chain mat has little or no structure providing transverse motion against the mined material, it is not unusual for the mined material simply to be tumbled in place as the mat moves under it rather than moving the mined material to the rear or discharge end of the machine. Thus, large lumps of the mined material such as coal tend to be further broken or pulverized thereby decreasing the overall value of the mined material. Furthermore, the juncture of the first portion of the conveyor system using chain mats, with the rearward portion or flight bar portion of the conveying system results in a point in the conveyor system where coal or mined material tends to accumulate without being continuously moved towards the rear of the mining machine. Finally, it will be appreciated by those skilled in the art that significantly greater tension must be maintained on a chain mat conveying system than on a flight bar conveying system. Thus, because of the required increased tension of the chain mat front conveyor and the additional gearing required to drive two conveying systems, the motor or drive means for the overall conveying system of this type mining machine must have significant work capacity.
Thus, from the afore-mentioned discussions of the prior art patents, it will be appreciated that heretofore both inexpensive and effective gathering and conveying systems have not been available. Accordingly, it is an object of this invention to provide methods and apparatus for inexpensively and effectively conveying mined material from the cutting head to the rear discharge area of a mining machine.
It is another object of this invention to provide a single conveyor which moves coal continuously from the auger cutting head to the rear of the mining machine.
It is still another object of this invention to provide a conveyor which requires minimum maintenance and is suitable for use with a dozer type gathering head.
It is yet another object of this invention to provide a conveyor for use with a narrow seam mining machine, which conveyor requires substantially less driving power than machines available heretofore.
Still another object of this invention is to provide a conveyor which will continuously move mined material away from the cutting head to avoid pulverization of large lumps of mined material.
These and other objects, which will become evident from the following drawings and detailed descriptions are accomplished by the present invention by the use of a single continuous conveyor used with a dozer type gathering head continuous mining machine. The conveyor comprises a driving means which drives or rotates a drive sprocket mounted at the rear portion of the mining machine. Two continuous and parallel drive chains extend from a small diameter turn around shaft at the front most portion of the dozer gathering head to the drive sprocket at the rear of the machine; which drive sprocket drive the chains. The turnaround shaft at the front of the machine has a diameter substantially the length of a link of said drive chains. A multiplicity of "flight bars" extend between and are attached to the two parallel drive chains such that mined materials dislodged by the mining machine is moved rearward by the flight bars as the drive sprocket imparts motion to the flight bars and chains combination.